Positive displacement pump



April 5, 1960 c w. MUSSER 2,931,310

POSITIVE DISPLACEMENT PUMP Filed Dec. 19, 1957 20 f zz 36k /521 w fl INVENTOR c. M aifazz A/wer United States Patent POSITIVE DISPLACEMENT PUMP C Walton Musser, Beverly, Mass.,

Shoe Machinery Corporation, poration of New Jersey assignor to United Flemington, NJ., a cor- The present invention relates to a positive displacement pump.

A purpose of the invention is to obtain pulseless operation of a positive displacement pump.

A further purpose is to reduce wear by assuring rolling contact between pumping elements and sealing surfaces.

A further purpose is to project a wave around elastic pump tubes to accomplish pumping without the necessity of axially rotating the tubes themselves.

A further purpose is to position the pump tubes in engagement both with the walls of the pump chamber and one another in such a way as to close off communication between the high pressure side and the low pressure side.

A further purpose is to operate a pump suitably at high pressures through a hermetic seal.

Further purposes appear in the specification and in the claims.

In the drawings I have chosen to illustrate a few only of the numerous embodiments in which the invention may appear, selecting the forms shown from the standpoints of convenience in illustration, satisfactory operation and clear demonstration of the principles involved.

Figure 1 is an axial section of a pump in accordance with the invention.

Figure 2 is a transverse section on the line 2-2 of Figure 1.

Figure 3 is a transverse section on the line 3-3 of Figure 1.

Figure 4 is a transverse section on the line 44 of Figure 1.

Figure 5 is a fragmentary axial section showing a modified bearing arrangement for the wave generator.

In the prior art, positive displacement pumps for liquid and the like usually involve the creation of a pulse which is objectionable in certain types of service.

The present invention makes possible positive pumping without the creation of a pulse, since there is never any time when the spaces on the pressure side of the seal between the pump tubes is not supplying fluid to the out put.

When the contour of the pumping elements is elliptoidal, the sum of the two active pumping areas rotating in the two pump chambers is a constant throughout rotation. Pulseless pumping is thereby obtained. Pumping action can also be accomplished by rotating a wave around the wall of two cooperating stationary tubes Sealing engagement between the tubes and the pump chambers is almost pure rolling without appreciable sliding.

One of the special advantages of the pump of the present invention is that it is possible to pump, even at high pressure, through a hermetic seal.

Considering first the form of Figures 1 to 4, I there illustrate a pump body 20 having two pump chambers 21 and 22 on parallel axes and communicating at cooperating sides at 23.

Each of the chambers is of circular cross section at any position transverse to the axis, but the diameter varies from a minimum at the ends to a maximum near the middle, as best seen in Figure 1.

Each of the chambers receives a flexible pump tube 24 or 25 which in unfiexed condition is suitably tubular, and of circular cross section and uniform diameter, but which is deflected, as later explained, so that the cross section is elliptoidal at the outside at 26 at the center and gradually merges into a circular contour at the outside at 27 at each end. 1

When reference is made herein to elliptoidal it is meant that the contour in general is that of two sine waves distributed around the circumference of a circle' and having their crossing points displaced degrees. By crossing points I mean the points of zero deflection. The sine waves are arranged so that the positive deflection from the circle equals the negative deflection in the troughs. Of course, advantage can be obtained from the invention without actually using an elliptoidal contour.

Where the pump body is of metal such as steel, stainless steel or bronze, and where the pump tubes are also of metal such as steel, stainless steel or bronze, the pump body and the tubes are preferably welded or otherwise sealed together and the tubes are preferably sealed to one another, at 28 at the ends. This is possible because the tubes do not rotate although they undergo wave motion.

Inside the tubes 24 and 25 are wave generators 30 and 31, which will suitably be of elliptoidal cross section near the middle and of circular cross section at the ends as shown. The assembly of the wave generators inside the tubes is described in my copending application Serial No. 717,709, filed February 26, 1958 for Adjustable Wave Generator, and may involve the use of separate inner and outer components for the Wave generators, although the wave generators can be forced into the tubes endwise before the assembly of the tubes to the pump chambers. When assembled in this manner the pump chambers should be split either axially or along 33 in Figure 1 to provide means of assembly.

Where the pump tubes comprise elastomer such as rubber, synthetic rubber, nylon, polytetrafluorethylene or the like, the seals 28 at the ends can simply be accomplished by tight pressure fit.

On one end of the wave generators are placed gears 32 and 33 which respectively mesh with one another, and the wave generator 30 carries driving shaft 34. An end closure 35 covers the gear end of the pump and provides a bearing at 36 for shaft 34. An end closure 37 covers the other end of the pump.

Inlet is provided at 20 and outlet at 20 or vice versa depending upon the direction of rotation.

Figure 5 illustrates a modified form of body 20' having an annular sealing recess 38 at one end provided with an O-ring 38' (suitably of figure 8 formation when viewed from the end) which seals on the outside of each tube 24 or 25, the inside of the tube being ,supported by outer race 40 of antifriction bearing 41, the inner race 42 of which is suitably engaged over boss 43 on the end of the wave generator. This construction is particularly suitable for elastomer pump tubes.

In operation, it will be evident that fluid received at the inlet is in the space between the pump tubes and the chamber walls, and in due process the progression of the pumping wave seals from access to the inlet. The effect of further progression of the pumping wave is to diminish the space between the pump tubes and the pumping chamber walls and thus expel the fluid under increased pressure. The respective wave generators are 90 degrees outof-phase with one another.

Manet!) View of iniieritioii anddisclosure variations and I gaging the tubes, deforming r'tiddifi'cationsto meet indi'vidualwhim or particular need will doubtless become evidenttto others skilled in the art to obtainall or part of. thelbenefits of my invention'withont co ying; the structure shown, and I, therefore, claim all such insofar as they fall within the reasonable spirit and scope of my claims.

Having thus describedjmy invention what I claim as' new and desire to secure by Letters Patent is:

11 In a pump, a pump body having two pump chamhers of circular cross section having large diameters at the centers and 'progressively smaller diameters toward the ,ends, communicating 'at adjoining sides, deformed fiexihl'ej pump tubes in the chambers in sealing. relation with the 'respectivepump chambers and with" one another,

an inlet' connection to'the' pump chambersi on] one side ofthe line of meeting ofthe pump tubes, an outlet connectiojnlm the'pump chambers on the other side of the lineiofmeetin'gof'the' pump tubes, rotatable'wave generators having elliptoidal' portions at the middle merging ii'lt'o'circular cross sections at the ends within and en- I4|L I a the same into elliptoidel form, and means for rotatingthe wave generators in unison out-of-phase with one another.

2. A pump of claim 1, in which the pump tubes are sealed to'the body at the ends. l

ILA-pump of claim 1, in combination with a seal engaging the outsides of the. pump tubes at the ends.

4. A pump of claim 1, in combination. with hearing means supporting the wave generators at' the ends and supporting rthe, ends: oi the pump: tubes,

5?. 'A pump of: claim 1, in which the metallic tubular elements. e 6. A pump ofclaim- 1, in which they tubes comprise elastomer tubular elements.

tubes comprise References C ited in the of this patent UNITED STATES PATENTS 

